Glycol modified PET (PETG), a polyester based solely on terephthalic acid (TPA) or an ester thereof, ethylene glycol, and cyclohexanedimethanol, is known in the art and is commercially available.
PETG is sometimes produced with a catalyst/stabilizer system which, given the rates at which polymer is produced, yields a polymer that barely meets color specifications. If color formation increases further, however, the polymer has lower value. In order to assure good color formation, a high purity terephthalic acid is sometimes used. The production of this high purity TPA adds significant cost to the process as a whole.
Thus, there is a need in the art for a system which produces PETG copolyesters with less color than the current catalyst/stabilizer system.